Justin Bieber's toxicology report from the night he was arrested in Miami last week has been released.

According to the report - obtained by TMZ - the pop star's urine was tested and he came up positive for marijuana and Xanax (prescription anti-anxiety medication).

The report shows he had traces of THC and Alprazolam, which is the key ingredient in Xanax, in his system.

He tested negative for cocaine, opiates, meth and other drugs.

At the time of his arrest the 19-year-old told cops he had taken anti-depressants provided to him by his mum, drank a beer and was smoking marijuana all day.

The troubled singer appeared in court last week via video link on charges of driving with an expired licence, driving under the influence and resisting arrest before his bail was set at 2,500 US dollars (£1,500).

On Wednesday Bieber pleaded not guilty and an arraignment at a Florida court was set for Valentine's Day.

Pop singer Justin Bieber arrives at a police station in Toronto (Image: Reuters)